Semiconductor device fabrication includes fabrication of microprocessors, logic, and memory devices. Such devices may be fabricated using a variety of techniques, including self-aligned patterning such as double patterning or quad patterning, gapfill processes, and other techniques. Some processes involve formation of structures that include silicon oxide and silicon nitride. Conventional techniques for forming such structures may be limited to patterning techniques that include both etch and deposition.